The ⁷Be content in runoff and sediment from different runoff plots under single rainfall event was analyzed.The result showed that ⁷Be concentration in runoff was relatively less than that in sediment and the average value was 0.92 Bq/L.However,the total loss of ⁷Be from runoff plots was great because much more runoff discharge was lost from runoff plots.It was estimated that 11%～33% of total loss ⁷Be in the whole cultivated plot ran off with runoff,and this had a great effect on the result of tracing soil erosion.The ⁷Be content in sediment was more than that in surface soil,especially in the weed and bush plot.At last,it was discovered that the grain size of sediment did not obviously influence the ⁷Be content in sediment,and surface erosion played an important role in the ⁷Be content of sediment.